At present cultivation is confined to the Armenian foot-hills--an uncertain arc of green from Aleppo to Mosul. But the railway strikes boldly into the deserted middle of the land, giving the arc a chord, and when Turco-German strategic interests no longer debar it from being linked up, through Aleppo, with a Syrian port, it will be the really valuable section of the Bagdad system. The railway is the only capital enterprise that Northern Mesopotamia requires, for there is rain sufficient for the crops without artificial irrigation. Reservoirs of population are the need. The Kurds who come for winter pasture may be induced to stay--already they have been settling down in the western districts, and have gained a reputation for industry; the Bedawin, more fickle husbandmen, may settle southward along the Euphrates, and in time there will be a surplus of peasantry from Armenia and Syria. These will add field to field, but unless some stronger stream of immigration is led into the land, it will take many generations to recover its ancient prosperity; for in the ninth century A.D. Northern Mesopotamia paid Harun-al-Rashid as great a revenue as Egypt, and its cotton commanded the market of the world[50]. Southern Mesopotamia--the Irak of the Arabs and Babylonia of the Greeks--lies desolate like the North, but is a contrast to it in every other respect. Its aspect is towards the Persian Gulf, and Rohrbach grudgingly admits[51] that down the Tigris to Basra, and not upstream to Alexandretta, is the natural channel for its trade. It gets nothing from the Mediterranean, neither trade nor rain, and every drop of water for cultivation must be led out of the rivers; but the rivers in their natural state are worse than the drought. Their discharge is extremely variable--about eight times as great in April as in October; they are always silting up their beds and scooping out others; and when there are no men to interfere they leave half the country a desert and make the other half a swamp. Yet the soil, when justly watered, is one of the richest in the world; for Irak is an immense alluvial delta, more than five hundred miles from end to end, which the Tigris and Euphrates have deposited in what was originally the head of the Persian Gulf. The Arabs call it the _Sawâd_ or Black Land, and it is a striking change from the bare ledges of Arabia and Iran which enclose its flanks, and from the Northern steppe-land which it suddenly replaces--at Samarra, if you are descending the Tigris, and on the Euphrates at Hit. The steppe cannot compare with the _Sawâd_ in fertility, but the _Sawâd_ does not so readily yield up its wealth. To become something better than a wilderness of dust and slime it needs engineering on the grand scale and a mighty population--immense forces working for immense returns. In a strangely different environment it anticipated our modern rhythm of life by four thousand years, and then went back to desolation five centuries